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As a part of the INQUA project “A Global Digital Database and Atlas of Quaternary Dune Field and Sand Seas”, 337 age records from the desert dunes of China and 20 from Mongolian dune fields have been compiled in the database. This has opened the possibility of exploring and synthesizing the Quaternary environmental changes in the Asian mid-latitudes dune fields directly from the on-site aeolian sand archives. This paper assessed the sand dune chronologies in terms of geographical distribution, data quality and their implications for late Quaternary palaeoenvironmental reconstructions. The available ages are concentrated mainly in the last 20 ka and many are from the fields of stabilized dunes in the eastern portion of the desert belt in northern China. The number of records and the ratio between the records of stable state and the total records could act as a proxy for the palaeoenvironmental interpretation. The aeolian sand activities deciphered from the chronological data in the eastern portion of the desert belt in northern China show a reasonable correlation with the general global climatic curves at the glacial–interglacial timescales. The limited aeolian sand records from the glacial period, however, hamper the understanding of the detailed features (e.g., forms and processes) of the dune fields during glacial times. In the last two millennia, however, there has not been any meaningful correlation between aeolian dune activity and climatic variation at the centennial time scales, probably due to the complexity of the aeolian sand systems and human interventions. Extending the coverage of dune chronology both temporally and spatially is urgently needed for a full understanding of the environmental changes in the dune fields. [ABSTRACT FROM AUTHOR]

Abstract: Identification of aeolian sand sources occurring in oases of desert environments is of great importance for understanding desertification processes and for developing strategies for sustainable development in arid regions. Combined with wind data and hierarchical cluster analysis, we analyzed the spatial characteristics of major and trace elements of sands sampled at the margins of the Minqin Oasis, northwestern China and its adjacent deserts (the Badain Jaran Desert and the Tengger Desert), with the purpose to identify the aeolian sand sources and their transport pathways in the region. The spatial distribution revealed by bivariate plots of Cr, Ni, Cr/V, Y/Ni, Al, V, Zr, Hf, Zr/Hf and ternary plots of major and trace elements showed that sands between the west (B – Badain Jaran Desert, BM – the dune belt between Badain Jaran and the Minqin Oasis and TNE – dune field located in the northeast margin of the Minqin Oasis) and southeast (TSW – dune field located in the southeast margin of the Minqin Oasis) sides of the oasis have different provenances, while the composition of sands in the Minqin Oasis (M) and in the dune field located in the south margin (TM) is associated with both. The variations in abundance of K, Rb, Ba and Sr were used as indicators of aeolian transport processes. Our results show that while aeolian sands from the Badain Jaran Desert can be transported over mountains and over long distances by northwest winds to the west sides of the Minqin Oasis, they cannot directly reach neither bypass the oasis to the east side. Our interpretation is that the oasis can act as an effective barrier to stop the migration of dune fields both in the Badain Jaran Desert and the Tengger Desert. However, the extensive occurrence of aeolian sands in the Minqin Oasis indicates that its role in preventing desert encroachment should not be overestimated. [Copyright &y& Elsevier]

Abstract: Although sand seas are located in arid regions, given that the proportions of dune areas vary greatly from region to region they are clearly influenced by other factors as well as aridity. This paper discusses the distribution pattern and major features of sand seas and large fields of stabilized dunes in northern China, and demonstrates the main influences on their development. It appears that the availability of onsite loose sediments, not wind strength, is critical to the occurrence of the sand seas on a regional scale. Tectonic, endorheic basins or areas of alluvial fans or forelands of mountain ranges are advantageous to the accumulation of fluvial sediments, and thus are ideal locations of large sand seas in an arid climate. The large dune fields currently stabilized by vegetation were active sand seas during the drier periods of the late Pleistocene and early Holocene. The distribution patterns of Chinese sand seas suggest that the height or size of the dunes in the sand seas are determined more by the availability of sands than any other potential factors. As the sand seas in China account for a large portion of deserts in the middle latitudes of the Northern Hemisphere (Taklamakan is the second largest sand sea on Earth), knowledge of these sand seas’ past changes is important for understanding climatic changes in the terrestrial regions of mid-latitudes. [Copyright &y& Elsevier]

Abstract: To identify the provenance of aeolian deposits in the extensive dune field in the Taklamakan Desert is of great importance for understanding the formation of this, the largest sand sea in China. The opinions from earlier studies are quite dipolar and are as follows: (a) local origin of the dune sands in different parts of the desert on the basis of various heavy mineral assemblages; and (b) strong homogenization of the sands in the entire Taklamakan on the basis of geochemical data from whole-rock samples. By separately examining the REE characteristics and major-elemental composition in coarse and fine fractions of the samples from aeolian deposits, this paper provides new data for interpreting sources of aeolian deposits in the Taklamakan. The sampling sites are distributed in four different fluvial systems, i.e. the areas of the Keriya River, Niya River and Cele River in the southern part and the northern margin near the Tarim River (Fig. 1). Our results show that there are some significant differences in concentrations of trace elements and in REE features between the coarse and the fine fractions of the aeolian sediment. The major-elemental and REE data suggest that the coarser sand is different from area to area in the desert rather than a homogenization of the entire basin. The fine fractions (mainly silts) are more homogenized. The regional difference of coarse fractions in the study areas is consistent with the fluvial and wind systems in the basin. This confirms that the sands are often mixed between the northern and southern parts but there is much less mixing along the east–west direction. It should be emphasized that not only glacial and aeolian processes but also fluvial and lacustrine processes have jointly contributed to the formation of the huge sand sea. In addition, little variation is found between old and young sands in two sediment sequences in the central part of the desert, indicating consistency of sand sources in a given site during the last 40ka. [Copyright &y& Elsevier]

The dry lands in China and Mongolia include sand seas, gravel deserts, stable sand dunes, desert steppe, steppe and scrub-woodlands environments distributed in a wide range of geomorphological and tectonic settings, from 155 m below sea level to more than 5000 m asl. In China, the sandy deserts and gravel deserts are located in the arid regions mainly west of the Helan Mountains (∼106°E), whereas the stable dune regions are distributed in the semi-arid areas east of the Helan Mountains. In Mongolia, deserts cover more than 40% of the country. They are mainly distributed in the southern and southwestern part of the country, in inter-mountain valleys and basins of the Altai Mountains, and in the Uvs Nuur Basin in northwestern Mongolia. The desert regions enclose mainly gravel desert (=Gobi) and comprise some areas with sand fields and dune fields, especially in western Mongolia.Relict frost wedges and moraines in the Chaidamu and Tarim basins of China indicate that the coldest time of the last glaciation occurred at 30–25 ka in these two areas. The stratigraphy of the dunes in the Badain Jaran Desert, high lake levels in the areas near and within the large deserts in China and in Mongolia suggest a much more humid climate in western China and in Mongolia during marine isotope stage three. However, the period after 24 ka to the end of the Pleistocene was mostly characterised by increased temperature and reduced precipitation in the Chaidamu and Tarim basins. Paleoenvironmental conditions in the eastern part of the Chinese desert belt were marked by an extensive widening of dune formation at ∼21–13 ka, reflecting a weaker intensity of East Asian summer monsoon. During the Holocene, higher lake levels, stratigraphy of dunes and results of palynological, isotopical and sedimentological analyses of lacustrine sediments in the western China and Mongolia suggest a few wetter periods, especially in the earlier part of the Holocene. The Holocene climatic conditions in the eastern part of the Chinese deserts have enabled stabilisation of dunes and formation of soils. The presently active dunes in this region are a result of desertification due to human influences. Recent investigations in the dry lands of China and Mongolia demonstrate broad regional differences that must be given attention for the understanding of palaeoclimates. [Copyright &y& Elsevier]

The Badain Jaran Desert, located in western Inner Mongolia, China, is characterized by an arid climate and by occurrence of large dunes and permanent lakes within the dune field. The main objective of this paper is to describe landscape evolution and climatic change in this desert since the late Pleistocene. Special attention is given to the dune and lake deposits as well as to the water chemistry of the lakes. On the megadunes of the desert several calcareous cementation layers and cemented plant roots were observed, indicating a relatively moister climate during the last 31,000 years. The present hypersaline lakes were filled with fresh or brackish water between 9 and 4 ka BP. On the basis of dune morphology and stratigraphy and lacustrine deposits, it is concluded that the enrichment of ions in the lakes and decline of their water surface result from aridification since the middle Holocene. The existence of more humid periods implies that the intensity of westerlies and Asian monsoons has changed periodically in this desert since the late Pleistocene. [Copyright &y& Elsevier]

The sedimentology and geomorphology of landforms along Keriya River, that traverse the Kunlun Mountains and Taklamakan Desert, were studied to examine the relationship between environmental change and landscape evolution in mountains and desert margins of the Taklamakan Desert. The region is divided into four geomorphic provinces: desert with active dunes and sand seas; desert pediment with fans; and foothills with deep gorges and glaciated mountains. A succession of three fans with dunes is differentiated on the basis of morphostratigraphy and relative weathering. The oldest fan and dunes are radiocarbon dated to ∼29 ka. This fan probably formed as a response to increased meltwater and sediment loads as glaciers retreated at the end of the local last glacial maximum in the Kunlun Mountains. Periglacial and glacial features throughout the region show that, during the last glacial, the snowline was lowered to ∼4000 m a.s.l., permafrost existed down to an altitude of ∼1800 m a.s.l., and that the likely temperature depression was ∼10°C. Radiocarbon dates on sand dunes and tamarisk hills help define the age of the lower two terraces to >1.5 ka and a few hundred years BP. This suggests that these terraces may have formed in response to increased precipitation during more humid times at ∼2 ka and during the Little Ice Age, respectively. The landforms and sediments in this region are polygenetic in origin, being transported, eroded and deposited by glacial, fluvial, aeolian and lacustrine processes. Particle size characteristics show that the fluvial sediments were substantially modified down basin. In contrast, the aeolian sediments were modified as they were transported toward the mountains from the desert by the dominant northerly winds. This complex interaction between environmental change and earth surface processes provides an important framework for examining the environmental consequences of the recently growing population and intensified agricultural activities along the mountain and desert margins of the Taklamakan Desert. [Copyright &y& Elsevier]

The INQUA Dunes Atlas project has developed a global digital database of chronological information for periods of inland or continental sand dune accumulation and stabilization. The database comprises information on the site location (including coordinates), dune type, and stratigraphic context, pertinent analytical information (e.g. luminescence procedures), and literature citations to the original data source. This paper discusses the background to the project, the concept and structure of the chronologic database that forms its core, and gives some examples of the scope of the database and ways in which it can contribute to greater understanding of the spatial and temporal variability in dune development. [ABSTRACT FROM AUTHOR]

The glacial environments on the Tibetan Plateau and the mechanisms for glacier and snow accumulation are discussed on the basis of new evidence of global temperature fluctuations and regional biome type changes. The biome types show that extensive snow and glacier fields could develop on the Tibetan Plateau with a temperature lowering of 7–9°C and precipitation decrease by 30–70%. Considering the cooling effect due to an increase of albedo resulting from increased snow and ice coverage, it is possible that the valley glaciers became enlarged to form large glaciers and snow fields during the Last Glacial Maximum. This new environmental modeling shows that the environmental conditions changed considerably during past glaciations. Such changes might have notable impacts on the monsoons and possibly on global climate. [Copyright &y& Elsevier]